Apparatus for forming sheet material



March 1935. F. A. PARKHURST APPARATUS FOR FORMING SHEET MATERIAL 5 Sheets-Sheet 1 Filed April 14,.1931

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UNITED STATES PATENT OFFICE Am April 14. 19:1, sci-m No. 529,996

- 2 Claims. (01. 10-14) This invention relates to apparatus for forming a web or sheet from plastic material. The apparatus of the invention is particularly adapted for forming a thin web of pyroxylin by extruding a I mass of pyroxylin in plastic condition under heavy pressure through a narrow annular orifice to form a tube which is slit subsequently and opened in the form of a flat sheet. It has been found by practical experience with apparatus for this pur- 10 pose that the sheet produced is subject to variations in thickness and frequently contains minute waves which may not be apparent to the eye and do not ailect the value of the material for certain uses but which render it unfit for purposes where a sheet of perfect uniformity is required.

It is the object of the present invention to provide an apparatus of this type adapted to minimizethe difliculties experienced with former apparatus and to produce a web or sheet of greater 20 uniformity.

Before explaining in detail the present invention, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illus- 25 trated in the accomp yin drawings, sincethe invention is capable of other embodiments and of being practiced or carried out in various ways. Also,itistobeunderstoodthatthephraseology or terminology employed herein is for the put- 30 pose of description and not of limitation, and it is. not intendedto limit the invention beyond theterms of the several claimsvhereto appended as 'comidered in'view of the prior art and the requirements thereof.

The invention will be more clearly understood from the following description in conjunction with the accompanying drawings: in which,

Fig. 1 is a sectional elevational view of an apparatus embodying the invention;

Fig. 2 is an elevational view of the same;

Fig.3isaplanviewofthesame;

Fig. 4 is an end elevational view of the same; and

Fig. 5 is a detail; sectional view of a portion of the apparatus.

An apparatus embodying the invention is illustrated in the accompanying drawings and comprises an extrusion press having a discharge nozzle 11. The discharge nozzle 11 is carried by a support 12 extending upwardly from a platform 13 and is provided with a flange 16 engaging a shoulder on the support. Bolts 14 passing through the support 12 and engaging the press 10 I hold the nozzle 11 upon the press 10. A support I 1'! of inverted U-shape is carried upon the platform 13 and is provided with a hollow depending portion 18 within which one end of a mandrel 19 is rotatably supported upon ball bearings 20 separated by spacers 21 and 21. A hollow casing 25 is centrally positioned within the nomle 11 5 andiscarrledbysupports22and23whichmay beformedasanintegralpartofthecasing. The

other end of the mandrel 19 is rotatably carried byballbearings26withinthecasing25. A strainer screen 62 is positioned between the casing 10 25 andtheinnersurfaceofthendmle 11 andis held in podtion by a perforate clamping ring 63 securedtothecasing25asbybolts64. Axial thrust ofthemandrelistakenbyballbearingsd interposed between a collar 7 on the mandrel and 15 a shoulder 6 on the casing 25. A shaft 53 is rotatably mounted in bearings formed in a bracket 5-1 carried by the support 1'! and carries a pinion 55 adapted to mesh with a bevel gear 56 keyed upon the mandrel 19. 'Ihe supports 12 and 17 20 are connected by tie rods 9.

A head 30 is rotatably supported near one end uponballbearings31positionedbetweenrings 32 and 33 threaded on the nowle. A sleeve 34 rotatablymountedonthenomleissecuredtothe 25 otherendofthcheadtiobyboltsfiandisprovidedwithataperedsurfaceaadaptedtoen- A knife 61 is secured upon the sleeve 58 between the support 17 and the guides 80.

In operation the worm 45 and the shaft 53 are rotated to rotate the head 30 and mandrel 19 respectively. The extrusion press 10 is then operated to force pyroxylin in plastic condition under heavy pressure through the orifice 48 to produce a tubular plastic sheet which travels 'over the guides 60 and is slit by the knife 61 to produce a sheet or web W of pyroxylin which is conveyed to other apparatus for drying. The supports 12 and 1'1, tie rods 9 and platform 13, preferably, are constructed as a single unit of suflicient weight to prevent relative lateral movement between mandrel and nozzle and to prevent any lateral movement of the nozzle that might be induced by the action of the extrusion press. Relative displacement of the mandrel and nozzle due to axial thrust of the mandrel caused by the enormous pressure ofthe plastic has been extremely difllcult to overcome and must be overcome to produce a satisfactory product. This displacement is minimized by the construction of the invention.

What I claim is:

1. In combination, spaced supports, a nozzle, one of said supports serving to support said nozzle, a mandrel carried at one end by the other support and projecting into said nozzle, spaced means within said nozzle for supporting the other end of the mandrel, a head rotatably mounted on said nozzle between said supports, an annular disc mounted on said head and surrounding said mandrel to provide an orifice therebetween, said disc having a portion extending axially into said nozzle and away from said orime, and auxiliary supporting means adjacent said disc for supporting said head.

2. In combination, spaced supports, a nozzle, one or said supports serving to support said nozzle, a mandrel carried at one end by the other support and projecting into said nozzle, spaced means within said nozzle for supporting the other end of the mandrel, and a head rotatably mounted on said nozzle.

FREDERIC A. PARKHURST. 

